Lars,
Also, offer an option to long-press on Undo/Redo buttons to popup and dropdown of History of Edits to undo/redo to any level. It also helps read what edits were made. Currently, it flashes a popup very briefly while undoing/redoing the change and disappears quickly with no clue of which edit was undone/redone - before we read the popup, it disappears. See popup dropdown on long-press in Nano Studio 2.